SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ed7dbecb4c3e723affd1be26cfa2589acdf8fda1d465c6f52cabf6a824c2e1' 
  AND token = 'x5U+MozMwo6QysktElcShMixckz/g4wqdAYBwov/1LU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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