SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '615d536338849dd7a9828cc296fe48e4403f7edce48fd90aafea679b2fb1836c' 
  AND token = 'nhqALmL6oTPOeaNF6f0xai+vcWeoPItcVPkuroKkrwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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