SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f62f00762586b590c749169b07d091e23315083b56a37014262d84e7b56b361' 
  AND token = 'LXjIq3j0QnRgN0ttFYErRItSa8pjlCFHpvTJuAH/iYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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