SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7786d0229f9f490921a401dce6e345e4a53e0d03b0ff1e20d57ed7502f34347b' 
  AND token = 'FUj0wKBL5kSu2tn630XW5zmSKtvNUDQuLuKTvYKj0zE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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