SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16a9863160b52eb4f4c7197afd85a6150bd1b35a4a9d537f38adae0eb6e8014f' 
  AND token = '8eqRzvLDSz/Jb2MHTm0mUgK22ntCSGPWvcEaJUYFf0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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