SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b74633eed5d6406dfaa1ad3db899390eaf18ec2864383f54b101a30a9548379' 
  AND token = '8EI5/jMkfOgN1SMcR2tdSZFOxFVsr02mlxrAgLfpR9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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