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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb91223491af0bf187b23f90cac5182051c66f3c583f6e4dfda7ad777e9cff4b' 
  AND token = 'Ns2RCBdZW4ovr1ZDl92Cpt4rwwysxf6F+TGP3Ra8D4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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