SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8968c6940fd44f40e882d81262b562160d13154fce83d43b0798702bff094c3c' 
  AND token = 'E2xMsdwwGV5EukK9y0/pUG7SqvJx965He74mqVOoTtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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