SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db6aa8e2145063fe84226263057559c9a17d85f608483c47b18e26c90ed304b0' 
  AND token = 'DvMk9BmNE8RvW5AQdfZUCR4PEXvpQbWnSLxMDi351y8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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