SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a1f9b641f9db52f1beece287f9d7c8da741565c67bacdaad78d801b54f2798a' 
  AND token = 'iWSWQltG9tUoAXYHxC58x/RByI0CFPVKwMuLkS6jTGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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