SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcb36586459460deb69c1481472505323e21ca044ee279aad98b9f3584efd6d5' 
  AND token = 'YupMHVdJAp1x7/sJB2grP9GYAwfqfmu7aVr71cLVUac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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