SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a245ad9c90e4ccab319b7df49394fab2e843b429aa490ccb1119ad9a6c7add78' 
  AND token = 'JPOVBwyQMCgoztst0POa6yrEyUq6xYmF8XGSEfKdwhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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