SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '859bd4f0fe5d37b2ce669eb64de0a241514c2570f66760712e78fc1c744c934f' 
  AND token = '1uIj6x6PdsVZFhL4PQ5Lxv/wiZDe4wY1ew4bLqIm1f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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