SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cef0d41ce59436da968d90d029a40217f4b1f0828635ffd88fa8916feca935ab' 
  AND token = 'N0mH/g9GLnZjQYBR7Cm9z3vxZoMbUjVmOgF9998vdq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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