SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf7702a8ecc4eeae65fa88e5c0e16d026ffdfc77ff1561678baf98c16a2166b5' 
  AND token = 'fZys3uOGtImZ91mRWOZCToDHpiJivd3jcVDKNpOQvCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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