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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df4c63bb61f9b9c71afa33f13a51d118d0a4187a5eadaf6684ca56b7c1e70c9f' 
  AND token = 'XLZlRdtyB1AGACJLrnLDK8ptUVFtA+mulUube9aXMiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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