SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c240c9fd203b819e7bd1658257729d08046597eba231f2ef489941dd36a6f67' 
  AND token = 'IIm1YuorGCzpnlfBdDRFRDKFu9f3HD3+vg47v9yo/Cs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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