SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21d2e892765b298e9e010cef3483495ee1b5dff0a3e9726ffaa538b6c235dba5' 
  AND token = 'VOJZ6bCvr29hhA7ebefb5ix+OMUlsmEk2I3WdotzNoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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