SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd27049babf62b1eeb0738611800f8159fad6205c897bd875f470823def431f08' 
  AND token = '6NvVAe7ReKXtOlDsi49JgHgytDTKcBPv9eU++GcYWOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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