SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef21965c1c6ba1df755dad245fdfd5fa710cd153b43c18c5596b8426250ebaed' 
  AND token = '+4zxQ7bMEnCgOzKp/w2q0z/VLJLD+jZyYEo0/gKNFmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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