SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0a75a943538954ded9b377f7a06bb6b8495f9f9dfcbd3c0f349b94f009cd88a' 
  AND token = 'ksDnJq3E4A3mefVAnU9o5zjBtdgY8yYQ80x1TvVO2Sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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