SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b3b818254107e0b70caa6265000143848a448739076724c2d8f2cd841aac173' 
  AND token = 'BZ+iP0rfC+hS7dU7KzUaDTvAbhWDvdlpYCNfKurnCDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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