SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12944b5cf6f3fa6f78aed6a22e63740f36ad057384662d8a36132e9907a86bc9' 
  AND token = 'CPHPDkQT5twT7ClP0xJ+3B0pbEjjSTEJm4nvwgWuQzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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