SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a41378d3c51d8eeafb564cd2ec1576dda6969e34238568103a7f89f484f2fb04' 
  AND token = 'LqZOGkLJLeMSnVYwiHBfBVhextoPEc21DDRwYSVnDJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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