SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d0ac97d3be2067e08f85ec395a057cd4dc05731a1d079945ee693cf81b17356' 
  AND token = 'CSW5gZeHsknD1BRDUlwqMy0b1aNI253l5QTeU7eU7UY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}