SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '415277dbed8632462eee81075a08b563011ee253913eb6d39a81dfdd79a429bc' 
  AND token = 'CeuxsEh1a1cmzhn8HvXMNYsXU+XAlKVGqEwguvp911w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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