SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7b85e4067468544fdb18006b2ee612ffbb3461f0a5d26f76b2fda410ea2b405' 
  AND token = 'ETU/HeGasBuf9xtzlNqJ+/BMjNBmHddzIdunc2IrHlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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