SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53e7e9d89cac875b1904bcc65008f6beafffbf2cf37bdbea549cf778892b82f6' 
  AND token = 'rj0eFsc28Gh4xlmFbp+wlk4QVKqvCkBwuBWFbSwJ72Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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