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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce68eb59bb9e49d7b21c817d8f2aa5335e2cc1bfa2972323b42d85d2a0f28928' 
  AND token = 'Hj68P2/AqFUa9nagQaHTlE70nyeuu2QyD+lIm6QbTlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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