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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '171b7fb496773fbf07980511e8b1757d944821f3791b95a0a6525f3bfd3ea51c' 
  AND token = '6ajOJD4KtcqBKapixuCjXi378ajoxw7+OMZG7iFlQ1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}