SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7a3bb276d9bac239a53f0443d32211881f838243831a2be4877b47f3f836671' 
  AND token = 'zCc4vgrazKqnpkajTyAapiVgWyI/yVujhUEkZpqiYNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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