SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a365d9ee89f186a103d1ab336c55375d2a79b0e057cce170b662eaf3a6f8dd75' 
  AND token = 'YNdOS7bc1NfMDebokaV7Li2UcbLd/+cZiA8sb406Mhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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