SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34cc8cb831e854ee9d36c68d792a1a2e3c2b7e8591e6b122ab5ee2b589e75d27' 
  AND token = 'saUGtcncdEFQ3G+UHPyjx9usmfUn6HtViuBhtipbB48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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