SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b2cbd8f6024df745ac90f3d1ac3bffd9adf3d2dd3d9af9fd88440bdf08271794' 
  AND token = 'rU1HfcMn0OR6z3rqS1rO75IjxDKSY6nasSOcgeFAaiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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