SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3aef421d8f1af26c119fd2203df711900bcfe374c6e84a7f6a6be52ef6ec5b54' 
  AND token = 'RDoHLyZhvZBfgr+RuyDOu0Ku5qAVEL/sbaBKvbSjgYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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