SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b3cf9c1fb6529246dd42966a4e2b52c03c05403b169d757deb9f2e48a6a1e0f' 
  AND token = '7zb25vnj7zJuxikeKwVVhTzgvP6/EhqFXvwbIHROJb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}