SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f291796eed70119bf00d60f1bba6363cce1eecbc33792950d7cd976319888c7d' 
  AND token = 'HasJvFpDDuQavyuglKuNhvd3EPHPfZn9XwcLbJMYZs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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