SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '578ec5fd4cf4fe8fd4189758cab03ef0a6396816b95ea1836028f00ee8191c4e' 
  AND token = '7JCQAlHzfHEvscIPVQfdBSwrrTMiyEnux0hm443SrBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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