SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b702620a0426567a3a6947a6462a14e92dd8711234a943185a951989caaafbc5' 
  AND token = 'pkVLleXhCBhAUwusE3qasLqyiCXD/1GGZbiPJA71Ut8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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