SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46fe92bb3cb562d5f5b33c7cd9cf48501055afed82a7e3430474b8f90c483ec4' 
  AND token = 'v1wiN+EGIloTiFJ9/rjlTiXVYgJJdQvw2vfpChuUvBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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