SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08c709e96a6ee3be6bbee577807220dd9b8eb904760651e733e0608b9fb5e4de' 
  AND token = 'oxdK8RKROcznhaC43F/5227rogSy50vzdodSiWQ1veg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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