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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d6e9df13e5ce87ccdc8d6b82635a4af03955e323c4d3a0f7d47724d3ebcb253' 
  AND token = '52ineipzj8fuuLWb7iuAvs8aCr18AdADxvz+S4HOdlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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