SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a97bc0d6a20b170784b596fee0a49550a2999eed859620e32cb6019054ecc019' 
  AND token = '0rkZorbVUd7Wb+ObCOBE2c4y8JmdT6wZuXpL1WGidSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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