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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8fca749f55f2dd9dad34d02ef940eb5267daf6c28731b004d11499a29c7a5c3' 
  AND token = 'nnZNSnZIj3hjmy5DXhsc0vlUAa+XNELy7AwtDf4nyiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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