SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c79afd71756dde6e5f154364455f2556689b0dac01287a6e8a581f7246929a22' 
  AND token = 'sT3EoTNqt7wiizP4eCoZ67fhBhruKx6Uh6rJOdPpKV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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