SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a7a29a2dd33d69b5b08679d06737742e03842ca29eef7fbb27b29d249e2056' 
  AND token = 'p6wfHxl6MlCdJPpvrGnp4BsuZsH1iOcnYB254jTOxYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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