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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6b397ac07b8ec63e3a67a4e82a1a6ac92cb87f4a01ab3771bc2823669e2c297' 
  AND token = 'eXizOOR8Y+BT1lYNQFd94mOEqPtmN/LQCfXndx0ZMUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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