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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e47b52ffc00d253ee0fe8e4de44c34facbd589cb6fc46a0d5692702075401a9f' 
  AND token = 'Y9CcJf4Z4Ss2UGJ/KzMyeHTBDoNpmmRv0ae7QUlcBP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}