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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73e3b4a063f8591e19dab60e61644e03f56845e578955992f7a193c9088137d3' 
  AND token = '7Hw8Dh0zYN1P+ShlXgTSIfAd6sL3ZtO6lmrtzOy3VWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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