SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f68dbb2b23573f9fadabe0f180bffadf2f0e3595c02be01bfaec800d0e3aa1' 
  AND token = 'ZP5IpbQJF8oVKNMGQQ3wD820V8IZmznAmhG9uh3JUQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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