SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b66c18248a57b385e98c0ded5c742a71c4ec622c84ce27ecd0ca1b4ea39884e0' 
  AND token = 'dUflsJlQnsyPz8ZvFMDo9pfqQIrgD+40xACtdww/Xw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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