SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdb55be2f3cf378602d8e8612960f3c3545a4f56d2706ede8d7ff7f84582f9e4' 
  AND token = '/MhvLsWTCo+SOrLCgdUL0yVUh6IjJ1b+Ky9VHugihcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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