SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cab985aaaaf0d3beafade001f3ddd354dfcd61b6f794e1731ffd7d50c8141f4' 
  AND token = 'g6sD5mTiLBJkAofY5b0WGxtrmoUv+uf7vh/CVts/DoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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