SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dc647813c56fba030b744e06101bf42a83516ecda09a6d640e320644bdc9671' 
  AND token = 'W1gKNL2UeE13zuWIplwpLEht0VIiR2w8tCB32AqalIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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