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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c16a8ceb70582a7710ffc9b839fc244f6a63721adff3d6e1a60dde867834b3cb' 
  AND token = 'K1I0ZaZj1ZR7g6PIdN4xwI7kt/VQwOG1KrQc3zcngU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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