SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f73c32a76a84a1576a81b0d5ee468e4edb29432ab2d579c0fe702addf41631f4' 
  AND token = 'ftbEuWyWVbm6H4plvLJ+FDDtKVeYNJWXtWqbVHOxbLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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