SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71a31e8f56431874656b28fad3f4e921e993d481d17bf711b2a046873654a422' 
  AND token = 'sU0u/43jnAIxr02IGyc0HvW6KC+m8Qwok7JwCIf/lMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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