SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f379336bfa0d46877df48256d28791a9836e1c594f5378a3d33717f2da9b82e' 
  AND token = '2DHWZBhaDgZtEt2eg+ZiJVYixzom4V9hQex7ohA+XCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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