SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b01f9fc939f3c503e51f5175a50546b226e9c842a5d7bcf670ff5529d312d842' 
  AND token = 'pWVgwpUijKr6io3SkY+Sw3AfPHuFXWr53zGXBLp7EyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}