SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a616f774065c5c583456c3ccc7cc5d6893d62522d9f37e901f2281712fafdfab' 
  AND token = '8qLZFhITBW+bZ8KQIzPddXeN1QlM9Qp+BtiTVtRHJ9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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