SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18326c9f75deded43787df6bae5934e9394ce317265170624fb354990aaa1025' 
  AND token = 'e4qLpmuv1FVRdeAVuV8YILGQOKnAkoqSpE1mFFTIXZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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